Compensating presser device for sewing machines



H. RlTTER Sept. 23, 1952 COMPENSATING PRESSER DEVICE FOR SEWING MACHINES Filed Feb. 15, 1951 3 2 Z Z. .Q.

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INVENTOB Herman Bit'er WITNESS ATTORNEY Patented Sept. 23, 1952 UNITED 'srA'rEs PATE T fort es;

Herman Rittcr, Cranford, N. J assignor to The Singer Manufacturing N. J., a corporationof New Jersey Application February 13, 1351, Serial No. 210,723 7 Claims. (01. 112-235) This invention relates to presser-devices for sewing machines and more particularlyto an improved presser-device of the compensating type which is constructed and arranged to eliminate undesirable inertia efiects during high speed op- 'eration.

The present invention, with regard to the low inertia feature, is a modification of the construction disclosed in the applicants prior application Serial No. 69,675, filed January '7, 1949, now Patent No. 2,550,499, April 24, 1951. As was pointed out in that application, the usual sewing machine feed mechanism imparts a lifting movement to the feed-dog opposing presser-foot during each stitch-forming cycle, and where the combined mass of the parts which must move with the presser-foot is relatively large, as with ordinary presser-device constructions, an objectionable inertia or momentum effect is experienced during operation at higher stitching speeds.

Due to this momentum effect, the prcsser-devi'ce' fails to return fully after each succeeding lifting movement, a condition which produces an apparent floating of the presser-device above the it will be understood that in comparison with I impact ofthe sewing machine feed mechanism'.

A further object is to provide a presser-device of the above character which is simple and economical in construction.

With the above and other objects and 'advan tages in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangement of parts hereinafter, set forth and illustrated in the accompanying drawings ofa preferred embodiment-of the invention inwhich: Fig. 1 is a fragmentary front end elevational View of a sewing machine with, the improved presser-device attached, and in which an equal thickness of work is disposed beneath each presser-foot.

Fig. 2 is a front elevational view, partly in section, of the presser-device of Fig. 1.'

Fig. 3 is a sectional view of a portion of the presser-device taken substantially along lin 3.--3

Company, Elizabeth,

- 2 of Fig. 2 and in which the presser-foot is illustrated in the position which it will occupy when unequal thicknesses of work are being stitched.

. Fig. 4 is a sectional view of a portion of the presser-device taken substantially along line 4'--4 of Fig. 1 and in which a portion of work fabrics are illustrated showing the position of the parts as in Fig. 3 when unequal thicknesses of work are being stitched.

which the feed-dog is successively raised to protrude above the throat-platefor the work feeding movement and then dropped beneath the throat-plate for the return movement. Journaled in the bracket-arm I i is a needle-bar l5 arranged to be. reciprocated by suitable mechanism (not shown) in timed relation with the complemented lower stitch-forming instrumentalities in the formation of stitches. Journaled in bearings It in the over-hanging bracket-arm adjacent the needle-bar is a presser-bar I! which is engaged and biased downwardly by a main presser-spring The instant presser-device is a unitary assem bly which is adapted to be attached to the presser bar in place of the usual presser-foot. .A body member I9 of the presser-device is formed with a slot 20 which is adapted to accommodate. the depending extremity of the presser-bar in order that the device maybe secured thereto by the usual presser-foot securingscrew 2|. The body member 19 is formed with a cylindrical bore 22 which is rearwardl inclined upwardly with respect to the longitudinal axis of the presser-bar. The bore 22 is extended upwardly by means of a tubular extension 23 carried by the body member l9, and the free extremity of the extension'is threaded to receive aknurled cap 2d. Disposed in the bore for turning'and endwise sliding movements is a cylindrical s1ide-b10'ck 25. A lightcoilspring 13 is disposed inthe bore between the block and the cap 24 to bias the block downwardly.

The body member I9 is formed at its lower extremity with two downwardly open vertical slots 26 and 21, which define side walls 28 and 29, re spectively, one at each side of said inclined bore. Slidably arranged in the slots 26 and 2! and engaged by the side walls 28 and 29 thereof are vertical pressure-shanks 30 and 3| of presserfeet 32 and 33, respectively. which are arranged side-by-side with respect to the'normal feeding direction of the feed-dog l4. In addition, the body member is provided with a horizontal pinclearance aperture 34 which is arranged transversely of the vertical slots 26 and 21 and opens at each side of the body member 19 through the side walls 28 and 29.

The presser-shanks are interconnected for relative compensating movements in opposite directions by a lever 35. This lever in the preferred embodiment illustrated in the drawings is a cylindrical pin which is fixed substantially at its mid-point in the slide-block and is operatively connected to each of the presser-shanks 30 and 3| by meansof pin embracing apertures 36 and 3'! formed in the presser-shanks respectively. The free ends of the lever are disposed in the pin clearance apertures 34 which affords suflicient clearance for limited rocking movements of the lever about the turning axisof the slideblock 25. In addition, the aperture 34 is elongated parallel to the axis of the bore 22 to permit sliding movement of the block 25 and the lever 35.

Referring particularly to Figures 3 and 4, it will be apparent that the interconnecting lever 35 is fulcrumed for turning movement about the axis of the cylindrical slide-block 25 and since the aperture 34 is wider than the lever diameter, a limited range of relative vertical movement is possible between the presser-feet when work of different thicknesses is introduced beneath the respective feet as illustrated in Fig. 4, in which panel A of. work material is doubled beneath presser-foot 32 while the single thickness of panel B extends both presser-feet. It is also pointed out that the downward pressure exerted by each presser-foot is substantially equal within the range of relative vertical positions. As the presser-feet are positioned at different elevations in response to difierent thicknesses of work, the lever pin 35 in turning about the cylindrical slide-block 25, assumes an angular relationship with each of the vertical presser-shanks 39 and SI as clearly shown in Fig. 4. In order to prevent binding between the pin and the shanks when this position of parts occurs, it is essential that suilicient clearance be provided therebetween. It is also .important that a tight and accurate fit be maintained between the shanks and the pin so that movement of one presser-foot will impart substantially an equal movement to the other presser-foot in an opposite direction. Both the clearance and the tight accurate fit are provided in the preferred embodiment by a novel formation of the shank-apertures which are tapered or chamfered inwardly from both sides as at 38 to leave remaining only a very narrow portion of the original aperture defining surfaces. This narrow portion is formed to embrace the pin in a relatively snug fit and to provide substantially a line contact therebetween so that within the limited range of turning movements of the'pin no binding will occurat the pin connection with the presser-foot shanks. It will be apparent that this desirable line contact between the pin and the shanks may be accomplished by a variety of modifications of the construction disclosed in the preferred embodiment, as for instance, by crowning or tapering the pin rather than the aperture.

When the presser-device of the present invention 'is applied to the sewing machine in placeof a presser-foot of ordinary construction, it is necessary that the downward extreme position of the presser-bar be limited. This may be readily accomplished as illustrated in Fig. 1 by a collar which is fixed to the presser-bar by set screw 4|. The collar 40 is positioned to abut a'presser-lifting sleeve 42 which. is slidable on the presser-bar and bears against the presser lifting lever 43 which is secured in the head H by a pivot screw 44. It is also important that the main presser-spring be preloaded in the stopped position as determined by the collar 40 so that during normal operation of the machine pressure exerted by the main presser-spring will be absorbed in the bracket-arm H by means of the stop collar 40 and the presser-feet will be biased by the light secondary spring I3 to oppose the action of the feed-dog. Under these conditions, when thesecondary spring l3 has considerably lower modulus of elasticity than the main presser-feet will be transmitted only to the leverpin 35, the slide-block 25 and the secondary spring [3, which because of the simplicity of the instant construction are extremely small in size and weight, thereby reducing the objectionable inertia effect to a minimum.

Having thus set forth the nature of the invention, what I claim herein is:

1. A detachable compensating presser-device for a sewing machine having a presser-bar comprising, a body member carried by said presserbar, a cylindrical bore formed in said body member, said bore having a longitudinal axis inclined with respect to said presser-bar, a cylindrical block slidably disposed in said bore, spring means biasing said block axially of said bore, a lever secured in said cylindrical block to extend transversely of the longitudinal axis and from opposite sides thereof, and two presser-feet arranged one at each side of said cylindrical bore in engagement with opposite ends of said lever.

2. In a presser attachment for a sewing machine having a presser-bar, a cylindrical block supported for axial sliding movement in a path inclined with respect to said presser-bar, spring means biasing said cylindrical block axially in one direction, a pair of presser-feet arranged one at each side of said cylindrical block, and a lever fixed in said cylindrical block, said lever supporting said presser-feet for correlative compensating movements about a fulcrum provided by said slide-block.

3. A presser-device for a sewing machine having a. work-feeding mechanism, a presser-bar, and a main presser-spring arranged to urge said presser-bar axailly in the direction of said workfeeding mechanism, said presser-device compris ing two spaced feed opposing presser-members, a lever disposed to engage each of said pressermembers, a block adapted to be supported from said presser-bar for sliding movement in a downwardly inclined path with respect to said presserbar, a lever-fulcrum afforded by said slide-block, said fulcrum providing an axis for correlative compensating movements of said presser-members, and a secondary presser-spring disposed to bias said slide-block downwardly in said inclined path, said secondary spring having a substantially lower modulus of elasticity than said main presser-spring.

4. A compensating presser-device for a sewing machine, comprising, a body member having a bore formed therein, a cylindrical slide-block disposed for limited turning movements and lengthwise sliding movements in said bore, a pin carried by said slide-block transversely thereof to partake of the limited turning and lengthwise sliding movements of said slide-block, two presser-ieet, a shank portion formed on each presser-foot, said body member formed to slidingly accommodate said shank portions one at each side of said bore, said shank portions each being formed with a tapered pin-receiving aperture to provide clearance for the turning movements of said pin.

5. A compensating presser-device for a sewing machine, comprising, a body member having a loore formed therein, a cylindrical slide-block disposed for limited turning movements and lengthwise sliding movements in said bore, a pin carried by said slide-block transversely thereof to partake of the limited turning and lengthwise sliding movements of said slide-block, two presser-feet, a shank portion formed on each presser-foot, said body member formed to slidingly accommodate said shank portions one at each side of said bore, said shank portions each formed with a pinreceiving aperture, the surface of said pin and the surfaces of said shanks bounding said apertures being formed to provide substantially a line contact therebetween throughout the range of possible turning movement of said pin.

6. A compensating presser-device for a sewing machine comprising a body member carried by said sewing machine, a spring pressed block iournaled for turning and endwise sliding movements on said body member, two presser-feet, means afforded by said body member for confining machine having a presser-bar comprising,

two presser-feet each having a presser-shank portion, a body member secured to said. presserbar, said body member having formed therein presser-shank engaging side walls, a block journaled for turning and endwise sliding movement in said body member, a pin carried by said block and disposed transversely of the turning axis of said block, operative connections betweeen each of said presser-shank portions and said pin, said body member slide walls being formed with a pin clearance aperture disposed to limit the range of movement of said pin about the turning axis of said block.

HERMAN BITTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENT 

